Adenosine induced monomorphic ventricular tachycardia.

Polymorphic ventricular tachycardia has been reported following the administration of adenosine for the treatment of SVT. We present a case of monomorphic ventricular tachycardia in a 75-year-old man following the intravenous administration of adenosine for stress testing.

Serial myocardial perfusion imaging with dipyridamole and rubidium-82 to assess restenosis after angioplasty.

UNLABELLED: The purpose of this study was to determine whether patients at high risk for clinical restenosis, following coronary angioplasty, could be identified by myocardial perfusion imaging performed with dipyridamole- 82Rb PET. METHODS: Forty-five patients (34 men, 11 women; mean age 58.5 yr) who had successful single-vessel angioplasty and were asymptomatic had dipyridamole-82Rb PET at 1 and 3 mo after the procedure. Abnormal flow reserve in the distribution of the angioplasty artery on PET was considered to be a decrease of > or = 1 perfusion grade in response to dipyridamole (assessed qualitatively from tomographic images and polar coordinate maps). Follow-up was performed for 6 mo postangioplasty. Clinical restenosis was defined as recurrent angina similar to that occurring before angioplasty and/or > or = 50% stenosis at the angioplasty site documented angiographically. We analyzed abnormal flow reserve in the distribution of the angioplasty vessel to identify which patients were at high risk for clinical restenosis. RESULTS: Fourteen patients developed clinical restenosis between 1 and 6 mo postangioplasty. Abnormal relative flow reserve in the distribution of the angioplasty vessel was present prior to the development of symptoms in 13 of 14 patients with clinical restenosis and in 8 of 31 patients without clinical restenosis (sensitivity 93%, specificity 74%, p < 0.0001). PET imaging successfully separated postangioplasty patients into groups with high (62%) and low (4%) risk of clinical restenosis. CONCLUSION: Abnormal relative flow reserve in the distribution of the angioplasty vessel on dipyridamole PET identifies asymptomatic postangioplasty patients at risk for clinical restenosis.

Silent myocardial ischemia during PET.

A resting perfusion defect detected during radioisotope myocardial perfusion imaging is generally thought to represent myocardial infarction. The administration of nitroglycerin during cardiac PET imaging results in improved resting defects, which suggests transiently abnormal resting perfusion with silent myocardial ischemia.

Marked PR interval prolongation simulating ST-segment elevation during exercise testing. A case report.

ST-segment elevation during exercise testing is usually indicative of severe proximal coronary artery disease. In this report, the authors describe a patient who underwent exercise stress testing and developed apparent ST elevation in the inferolateral leads. However, noninvasive imaging studies revealed no evidence of myocardial ischemia or other recognized causes of this exercise electrocardiographic (ECG) finding. Analysis of the ECG tracings showed that ST elevation was produced by marked prolongation of the PR interval, super-imposing the P wave on the J-junction of the preceding QRS-ST-segment complex. The authors suggest that marked PR prolongation during exercise may mimic ST elevation, and this possibility should be considered in patients with this exercise ECG finding in whom cardiac evaluation is negative.

Exercise echocardiographic correlates of transient dilatation of the left ventricular cavity on exercise thallium-201 SPECT imaging.

Transient dilatation of the left ventricular cavity on exercise thallium perfusion imaging is recognized as a marker of significant coronary disease, but the mechanisms that produce this finding are not fully understood. We studied 32 patients who underwent exercise thallium imaging and exercise echocardiography to determine the changes in left ventricular cavity size that underlie transient dilatation. Left ventricular area from the apical four-chamber view was used to approximate left ventricular cavity size. There were 24 patients who did not have transient dilatation (group 1) and 8 patients who did have transient dilatation (group 2) on thallium imaging. Systolic area decreased from rest to exercise in group 1 patients but not in group 2 patients. There was no significant change in diastolic area from rest to exercise in either group 1 or group 2 patients. Thus, exercise-induced systolic dysfunction, manifested as a failure to decrease left ventricular systolic cavity size in exercise, may be an important mechanism in producing scintigraphic transient dilatation.

Disappearance of a left ventricular aneurysm on radionuclide ventriculography due to formation of a mural thrombus.

Radionuclide ventriculography is an accepted method for diagnosing left ventricular aneurysms, but false-negative studies have been associated with a mural thrombus filling the left ventricular cavity. We describe a patient with a left ventricular aneurysm due to myocardial infarction whose aneurysm scintigraphically "disappeared" from serial radionuclide ventriculograms. This was documented echocardiographically and pathologically to be due to the formation of a large mural thrombus. Review of the literature suggests that radionuclide ventriculography and echocardiography may be complementary techniques in the diagnosis of left ventricular aneurysm. Echocardiography may remain diagnostic when a mural thrombus has caused the loss of the characteristic scintigraphic findings on radionuclide ventriculography.

Left ventricular cavity-to-myocardial count ratio: a new parameter for detecting resting left ventricular dysfunction directly from tomographic thallium perfusion scintigraphy.

Patients with reduced left ventricular function or aneurysms have cavities that appear dark on SPECT thallium scintigrams. We hypothesized that a quantitative index, which relates thallium activity in the left ventricular cavity to that in the myocardium (C/M ratio), could provide information on left ventricular function. A group of 80 patients who had both exercise SPECT thallium imaging and cardiac catheterization were studied. The C/M ratio was obtained from the short-axis tomogram on both exercise and rest images. Counts in a 2 x 2 pixel region of interest in the left ventricular cavity were divided by the number of counts in the "hottest" area of the myocardium. Plotting the angiographically determined ejection fraction against the C/M exercise and rest ratios, we observed a linear correlation between ejection fraction and both C/M ratios, r = 0.65 for C/M exercise and r = 0.67 for C/M rest ratio (p < 0.00001). Using data from 12 normal cardiac catheterization patients, we established the lower limit of normal; 50% for ejection fraction and 0.40 for the C/M ratios. A C/M exercise ratio < or = 0.40 identified 26 of 31 patients with an ejection fraction < or = 50%. A C/M exercise ratio > 0.40 identified 39 of 49 patients with an ejection fraction > 50%. These calculations yielded a sensitivity of 83% and specificity of 78% for the C/M exercise ratio. A similar analysis for C/M rest ratio revealed sensitivity of 61% and specificity of 92%. The present study shows that an abnormal C/M ratio correctly distinguishes patients with abnormal from normal ejection fractions with an accuracy of 81%. The C/M ratio is easily obtained, requires minimal processing time and is highly reproducible. These attributes may enable this index to add supplementary information regarding left ventricular function in addition to perfusion from thallium imaging.

Unsuspected cardiac abnormalities in the acquired immune deficiency syndrome. An echocardiographic study.

To investigate the frequency of unsuspected cardiac abnormalities in AIDS, M-mode and two-dimensional echocardiograms were performed on 27 homosexual males with this syndrome. Twenty-one homosexual males without the disease were used as controls. Subjects with clinical heart disease or a history of intravenous drug abuse were excluded. Fractional shortening was reduced in eight patients (30 percent) and in one control (5 percent) (p less than 0.05). Pericardial effusions were found in seven patients (26 percent); one control subject had a small effusion (5 percent) (p = 0.05). Overall, echocardiographic abnormalities were found in 13 of 27 patients (48 percent) compared with 2 of 21 control subjects (10 percent) (p less than 0.02). We conclude that although often not diagnosed clinically, the incidence of cardiac involvement in AIDS is high.

Pulsed and continuous wave Doppler echocardiographic assessment of valvular regurgitation in normal subjects.

To assess the prevalence and flow characteristics of valvular regurgitation detected by Doppler echocardiography in normal subjects, pulsed and continuous wave Doppler studies were performed in 100 adult volunteers without evidence of heart disease. Evidence of valvular regurgitation was present in 73% of subjects. There were 46 subjects with regurgitation of one valve, 24 with regurgitation of two valves and 3 with regurgitation of three valves. Right-sided regurgitation was significantly more common than was left-sided regurgitation (81 versus 22 valves, p less than 0.01). Regurgitant flow was never detected farther than 1 cm from the valve by pulsed Doppler study. Tricuspid regurgitation was detected in 50 subjects and was characterized by a holosystolic velocity signal; a complete spectral envelope was recorded in 32 subjects. The peak velocity of the regurgitant jet for this group was 1.7 to 2.3 m/s (mean 2.0 +/- 0.2). Thirty-one subjects were found to have pulmonary regurgitation with a peak velocity of 1.2 to 1.9 m/s (mean 1.5 +/- 0.2); no subject demonstrated regurgitant flow in early diastole. There were 21 subjects with mitral regurgitation; continuous wave Doppler signals were always of low intensity with a poorly defined spectral envelope and an absence of high velocities. Peak velocities ranged from 1.1 to 4.4 m/s (mean 2.3 +/- 0.9) and in 19 subjects were less than 3.5 m/s. The mean age of subjects with mitral regurgitation was significantly higher than that of subjects without mitral regurgitation (p = 0.01). Aortic regurgitation was detected in only one subject. This study provides further evidence that valvular regurgitation is frequently detected by Doppler echocardiography in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of continuous-wave Doppler ultrasound to evaluate and manage primary pulmonary hypertension.

Doppler ultrasound was used to assess the response to serial drug testing in a patient with primary pulmonary hypertension. There was a close correlation between the pressure estimated by Doppler and the pulmonary arterial systolic pressure measured invasively (r = 0.98). Continuous-wave Doppler ultrasound, although not a substitute for initial Swan-Ganz catheterization, may obviate the need for repeat invasive procedures and permit closer monitoring of patients during treatment.

Radiographic pseudofracture of bipolar pacemaker wire.

We present a case in which the radiographic appearance of a bipolar pacing lead mimics a wire fracture. Recognition of this normal finding--due to lead construction--will help avoid erroneous diagnosis of wire fracture on chest x-ray films.

Quantitative assessment of pulmonary hypertension in patients with tricuspid regurgitation using continuous wave Doppler ultrasound.

Doppler ultrasound examination was performed in 69 patients with a variety of cardiopulmonary disorders who were undergoing bedside right heart catheterization. Patients were classified into two groups on the basis of hemodynamic findings. Group I consisted of 20 patients whose pulmonary artery systolic pressure was less than 35 mm Hg and Group II consisted of 49 patients whose pulmonary artery systolic pressure was 35 mm Hg or greater. Tricuspid regurgitation was detected by Doppler ultrasound in 2 of 20 Group I patients and 39 of 49 Group II patients (p less than 0.001). Twenty-six of 27 patients with pulmonary artery systolic pressure greater than 50 mm Hg had Doppler evidence of tricuspid regurgitation. In patients with tricuspid regurgitation, continuous wave Doppler ultrasound was used to measure the velocity of the regurgitant jet, and by applying the Bernoulli equation, the peak pressure gradient between the right ventricle and right atrium was calculated. There was a close correlation between the Doppler gradient and the pulmonary artery systolic pressure measured by cardiac catheterization (r = 0.97, standard error of the estimate = 4.9 mm Hg). Estimating the right atrial pressure clinically and adding it to the Doppler-determined right ventricular to right atrial pressure gradient was not necessary to achieve accurate results. These findings indicate that tricuspid regurgitation can be identified by Doppler ultrasound in a large proportion of patients with pulmonary hypertension, especially when the pulmonary artery pressure exceeds 50 mm Hg. Calculation of the right ventricular to right atrial pressure gradient in these patients provides an accurate noninvasive estimate of pulmonary artery systolic pressure.

Determination of tissue concentrations of vinca alkaloids by radioimmunoassay.

Methodology for the determination of tissue concentrations of the vinca alkaloids has been developed with a specific radioimmunoassay (RIA). Data obtained with this RIA were compared with those obtained following direct administration of radiolabeled vinblastine. Distribution of radiolabeled vinblastine was also compared between control rats and those bearing the transplantable tumor Lymphoma 8. Vindesine concentrations in various rat tissues were determined via RIA over a 52-hr period.